public class StringDemo1 {
    /**
     * String API示范
     * @param args
     */

    //字符串大小写转换
    public static void main(String[] args) {
        String s = "hello";
        s = s.toUpperCase();
        System.out.println(s);

        String s1 = "Hel汉字lo9";
        System.out.println(s1.toLowerCase());
    }
}
